Answer: Water canal system.
- A Water canal system
- B Open blood system
- C Tracheal air system
- D Lateral line system
Correct answer: A. Water canal system
Explanation: Sponges (Porifera) have a water canal system driven by choanocytes, bringing in food and oxygen and removing wastes.
Moving across the animal phyla, body organisation becomes progressively more complex: from no symmetry and cellular organisation (Porifera) through radial/diploblastic (Cnidaria), bilateral/acoelomate (Platyhelminthes), pseudocoelomate (Nematoda), to a true coelom with full organ systems (Annelida and beyond).
Concept context
Phylum-level classification of the animal kingdom from Porifera to Chordata, based on body symmetry, coelom, and segmentation. One of the most example-heavy chapters for NEET.